Help anyone? Copper head gasket

[srech77]

Hey all -

I'm having Eric at Sundial do some porting work on my cylinders, and I'm also getting some Jemco chambers made. Eric recommended using a thinner copper head gasket to help raise compression, but this is something I've never done.

Do I just use liquid copper build-a-gasket stuff, or is there a stiff metal copper gasket available for purchase somewhere.

I've e-mailed Eric a few times, but my guess is that he's just super busy, so I feel bad sending him so many messages. Can anyone out there speak to this?

Would appreciate your help - thanks.

[tz375]

You have choices. I would use a Cometic regular gasket and machine some off the head to raise compression.

Or you can buy a copper gasket.

[srech77]

Okay, thanks. And when you say cometic, you mean just the factory suzuki replacement gasket?

And if I wanted to buy a gasket, where can I find a copper one for this bike??

[srech77]

You have choices. I would use a Cometic regular gasket and machine some off the head to raise compression.

Or you can buy a copper gasket.

Also, if I were to machine the head, what amount are we talking here? Like .5mm or something?

thanks -

[pull the wire]

You have to contact Cometic directly. http://www.cometic.com/" onclick="window.open(this.href);return false; Just call the tech line and the experts will help you with the choices. You will need to tell them the thickness you desire, bore size and material you want. I would go 1mm over on the bore diameter because of the inconsistencies of the machining of the bore centerlines from the factory. Excellent products and service.

Tell them what you want and they ship it directly to you. Should be around $57 delivered

Hope this helps

[srech77]

You have to contact Cometic directly. http://www.cometic.com/" onclick="window.open(this.href);return false;" onclick="window.open(this.href);return false; Just call the tech line and the experts will help you with the choices. You will need to tell them the thickness you desire, bore size and material you want. I would go 1mm over on the bore diameter because of the inconsistencies of the machining of the bore centerlines from the factory. Excellent products and service.

Tell them what you want and they ship it directly to you. Should be around $57 delivered

Hope this helps

I will do that, and it does help a bit ... but as someone who is not familiar with these modifications, how do I know what thickness to go with on the head gaskets? And I already have the cylinders overbored 1mm, so I don't know if that's what you mean in regards to going 1 mm over when ordering the gasket size? Sorry .... I'm just trying to figure out how to not blow up my bike once I get my jugs back from Eric, and my chambers finally arrive. I've already put different jets in the carbs (don't know if they are the right size since I haven't been able to run it without the parts I need), and I have the new pistons, rings, etc. (thermal coated), but I've never installed a one-off head gasket before so I'm just trying to get this part nailed down.

thanks for your help -

[srech77]

I was looking at a different post where someone melted their head ... they said they were using a cometic gasket when that happened.

I don't plan on racing this bike, it's more just an aggressive street bike ... just trying to get the scoop on whether or not it's in my best interest to do a copper gasket (he was saying maybe .010" or .012") and be able to ride the bike while maintaining reliability, or if I should just stick with the stock alum. gasket.

It will have the ported heads, chambers, and rejetting, with stock air box, so if I can source a copper gasket and gain something noticeable from it power wise while not blowing up my bike, then I'll look into it, but if I can just use the alum gasket with good results, then I'll probably do that...

[pull the wire]

I assume you and the engine builder have a target for engine performance and reliability. The aftermarket and stock Suzuki head gaskets are lacking in quality of fitment. The cometic gaskets are generally made for you 1 at a time to your specs. That is something you and your builder need to discuss and make decisions about before ordering gaskets from cometic. The cometic gaskets are so well built that if the cylinders are not perfectly bored on center, which they generally are not, The gasket may over hang into the bore of the cylinder. That's why I ask for 1mm larger bore than actual as to have a little cushion or wiggle room.

[srech77]

Noted ... there is no builder in this situation. I am just a normal garage mechanic working on my personal bike. I have restored the bike without cracking the motor. When I originally purchased it, the previous owner holed/melted the right piston, so I bored it +1mm, put everything back together and kept going.

I'm asking these questions now because of the porting Eric is doing for me, and the chambers I am having made, which should be done soon. I have the bike sitting in the garage with heads and jugs off, and I have a new set of ceramic/thermal pistons and rings (1mm over) ready to be put in once I get the jugs back.

I currently have the stock carbs with larger jets installed, so this is where I'll start once I get everything back. I'm tempted at this point to just use the stock gaskets since I have them ... maybe I'm lost, idk... :/

I noticed on the cometic website, they don't list the T500 for suzuki models they have on file. If I call them, will they know what gasket I'm talking about, or do I need to send them a gasket so they can replicate a copper one?

[jeff kushner]

They will know what you are talking about, just tell them that you have a vintage motorcycle and then give them the year, make and model. PAy special attention to properly fitting them when they arrive. With the t500( and GT750 for that matter), there is enough "play" in the headbolts that you can end up leaving part of the gasket into the cylinder which can cause you to pull out wondering why it's detonating. You can also send the heads to RK engineering and they will cut squish bands into the heads but be wary of just "cutting .5mm off for higher compression"....it's something a lot of guys used to do as a matter of course but with the swill sold for gas now, it's not nearly as forgiving.

jeff

[srech77]

Thanks Jeff - would it be advisable to tell Cometic to increase the inside diameter of the gasket by 1mm just to be safe, or just the spec they have should be good?? Also, I can't seem to get anyone to speak to what thickness the gasket should be ... I know the factory replacement gasket I have looks pretty darn thin, so I can't imagine too much thinner would be workable ... but idk.

And could you put the link for RK engineering in a post ... I Googled it, but there are several different companies around the world that go by RK "something" in regards to automotive parts, etc.

thanks again -sterling

[srech77]

They will know what you are talking about, just tell them that you have a vintage motorcycle and then give them the year, make and model. PAy special attention to properly fitting them when they arrive. With the t500( and GT750 for that matter), there is enough "play" in the headbolts that you can end up leaving part of the gasket into the cylinder which can cause you to pull out wondering why it's detonating. You can also send the heads to RK engineering and they will cut squish bands into the heads but be wary of just "cutting .5mm off for higher compression"....it's something a lot of guys used to do as a matter of course but with the swill sold for gas now, it's not nearly as forgiving.

jeff

I just called Cometic and ordered some gaskets, very simple. Looks like they have .010 and .020 on file in copper ... so to be on the safe side, I ordered 2 gaskets at .020. Down the road if I get things dialed in right, maybe I can move to the .010. He also said they cut them with a tolerance, so I shouldn't need to make it any larger on the inside to avoid hanging into the cylinder.

Now I was thinking of maybe just milling the head enough to clean it up nice and smooth the surface (maybe .010) or if I can get the right RK Engineering line, I will call them and see if I can have them cut me some squish bands for my heads ...

[pull the wire]

The .020 gasket and a nice flat smooth lightly milled head will work great. Just enough to be sure they good and flat. I would wait till you dial it in before trying head modifications.

[srech77]

The .020 gasket and a nice flat smooth lightly milled head will work great. Just enough to be sure they good and flat. I would wait till you dial it in before trying head modifications.

I pm'd you back .. and I agree, these mods will be it for now. Once I get the jugs back from Eric, I will probably get them sandblasted and powdercoated, and if I get it back together with no issues after that, I probably won't mess much with it performance wise.

Famous last words, lol.

[jeff kushner]

I can do better then a link!

Here is Kelsey's number at RK Engineering.... 208-852-3221

If it were my bike, I would cc each head then make the decision on gasket thickness or getting them cut based on the results. You very well might have two different volumes which you will need to address. I have heard of some guys over-sizing the gasket by .2-1mm and I wouldn't necessarily argue with them about it but for me personally, I like a nice, smooth, even fit between barrel, gasket and head but I doubt a small over-size would hurt anything but it does change volume...whether it's enough to cause impact, I'm not sure. I'd rather say when I'm not sure then to pretend I know something that I don't.

jeff